Blackleg, known as Phoma lingam, is a sneaky fungal disease targeting our beloved brassicas like broccoli. It’s a bit of a drongo, causing dark, sunken spots on the stems and yellowing leaves, eventually leading to wilting and sometimes plant death.
The fungus spreads through infected seeds, plant debris, and splashing water. Warm, wet conditions create the perfect breeding ground for this unwanted garden guest.
Prevention
When it comes to blackleg, prevention is your best bet, mate. Keep these top tips up your sleeve:
- Choose resistant varieties: Go for broccoli and other brassica varieties that are resistant to blackleg. You’ll find them in seed catalogues or at your local nursery.
- Certified seed: Purchase certified disease-free seed to reduce the risk of introducing blackleg into your garden.
- Crop rotation: Rotate your brassicas every 3-4 years to break the disease cycle and prevent blackleg buildup in the soil.
- Garden hygiene: Keep your garden clean by removing plant debris and weeds, which can harbour fungus. Please make sure to disinfect your gardening tools to avoid spreading the disease.
- Water wisely: Water your plants early in the day and at the base, avoiding wetting the foliage. This helps reduce the spread of the disease through splashing water.
Treatment
If blackleg has already gatecrashed your garden party, keep hope! Try these treatment strategies:
- Remove infected plants: As soon as you spot signs of blackleg, remove the affected plants and dispose of them in the rubbish, not the compost. This helps stop the disease from spreading.
- Prune lower leaves: Remove lower leaves from healthy plants to reduce contact with the soil and minimise the risk of infection.
- Fungicides: Apply a suitable fungicide, like those containing mancozeb or chlorothalonil, following the label instructions for application rates and timing. These can help control the disease if applied early and consistently.
- Boost plant health: Keep your plants in tip-top shape by providing proper nutrition, water, and care. Healthy plants are more resistant to diseases like blackleg.